/*
 * Copyright 2017 Google
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import <XCTest/XCTest.h>

#import "FTreeSortedDictionary.h"
#import "FLLRBNode.h"
#import "FLLRBEmptyNode.h"
#import "FLLRBValueNode.h"

@interface FLLRBValueNode (Tests)
- (id<FLLRBNode>) rotateLeft;
- (id<FLLRBNode>) rotateRight;
@end

@interface FTreeSortedDictionaryTests : XCTestCase

@end

@implementation FTreeSortedDictionaryTests

- (NSComparator) defaultComparator {
    return ^(id obj1, id obj2) {
        if([obj1 respondsToSelector:@selector(compare:)] && [obj2 respondsToSelector:@selector(compare:)]) {
            return [obj1 compare:obj2];
        }
        else {
            if(obj1 < obj2) {
                return (NSComparisonResult)NSOrderedAscending;
            }
            else if (obj1 > obj2) {
                return (NSComparisonResult)NSOrderedDescending;
            }
            else {
                return (NSComparisonResult)NSOrderedSame;
            }
        }
    };
}

- (void)testCreateNode
{
    FTreeSortedDictionary* map = [[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
            insertKey:@"key" withValue:@"value"];
    XCTAssertTrue([map.root.left isEmpty], @"Left child is properly empty");
    XCTAssertTrue([map.root.right isEmpty], @"Right child is properly empty");
}

- (void)testGetNilReturnsNil {
    FImmutableSortedDictionary *map1 = [[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                        insertKey:@"key" withValue:@"value"];
    XCTAssertNil([map1 get:nil]);

    FImmutableSortedDictionary *map2 = [[[FTreeSortedDictionary alloc] initWithComparator:^NSComparisonResult(id obj1, id obj2) {
        return [obj1 compare:obj2];
    }]
                                        insertKey:@"key" withValue:@"value"];
    XCTAssertNil([map2 get:nil]);
}

- (void)testSearchForSpecificKey {
    FTreeSortedDictionary* map = [[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                        insertKey:@1 withValue:@1]
                                       insertKey:@2 withValue:@2];

    XCTAssertEqualObjects([map get:@1], @1, @"Found first object");
    XCTAssertEqualObjects([map get:@2], @2, @"Found second object");
    XCTAssertNil([map get:@3], @"Properly not found object");
}

- (void)testInsertNewKeyValuePair {
    FTreeSortedDictionary* map = [[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                        insertKey:@1 withValue:@1]
                                       insertKey:@2 withValue:@2];

    XCTAssertEqualObjects(map.root.key, @2, @"Check the root key");
    XCTAssertEqualObjects(map.root.left.key, @1, @"Check the root.left key");
}

- (void)testRemoveKeyValuePair {
    FTreeSortedDictionary* map = [[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                        insertKey:@1 withValue:@1]
                                       insertKey:@2 withValue:@2];

    FImmutableSortedDictionary* newMap = [map removeKey:@1];
    XCTAssertEqualObjects([newMap get:@2], @2, @"Found second object");
    XCTAssertNil([newMap get:@1], @"Properly not found object");

    // Make sure the original one is not mutated
    XCTAssertEqualObjects([map get:@1], @1, @"Found first object");
    XCTAssertEqualObjects([map get:@2], @2, @"Found second object");
}

- (void)testMoreRemovals {
    FTreeSortedDictionary* map = [[[[[[[[[[[[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                                  insertKey:@1 withValue:@1]
                                                 insertKey:@50 withValue:@50]
                                                insertKey:@3 withValue:@3]
                                               insertKey:@4 withValue:@4]
                                              insertKey:@7 withValue:@7]
                                             insertKey:@9 withValue:@9]
                                            insertKey:@20 withValue:@20]
                                           insertKey:@18 withValue:@18]
                                          insertKey:@2 withValue:@2]
                                         insertKey:@71 withValue:@71]
                                        insertKey:@42 withValue:@42]
                                       insertKey:@88 withValue:@88];
    XCTAssertNotNil([map get:@7], @"Found object");
    XCTAssertNotNil([map get:@3], @"Found object");
    XCTAssertNotNil([map get:@1], @"Found object");


    FImmutableSortedDictionary* m1 = [map removeKey:@7];
    FImmutableSortedDictionary* m2 = [map removeKey:@3];
    FImmutableSortedDictionary* m3 = [map removeKey:@1];

    XCTAssertNil([m1 get:@7], @"Removed object");
    XCTAssertNotNil([m1 get:@3], @"Found object");
    XCTAssertNotNil([m1 get:@1], @"Found object");

    XCTAssertNil([m2 get:@3], @"Removed object");
    XCTAssertNotNil([m2 get:@7], @"Found object");
    XCTAssertNotNil([m2 get:@1], @"Found object");


    XCTAssertNil([m3 get:@1], @"Removed object");
    XCTAssertNotNil([m3 get:@7], @"Found object");
    XCTAssertNotNil([m3 get:@3], @"Found object");
}

- (void) testRemovalBug {
    FTreeSortedDictionary* map = [[[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                         insertKey:@1 withValue:@1]
                                        insertKey:@2 withValue:@2]
                                       insertKey:@3 withValue:@3];

    XCTAssertEqualObjects([map get:@1], @1, @"Found object");
    XCTAssertEqualObjects([map get:@2], @2, @"Found object");
    XCTAssertEqualObjects([map get:@3], @3, @"Found object");

    FImmutableSortedDictionary* m1 = [map removeKey:@2];
    XCTAssertEqualObjects([m1 get:@1], @1, @"Found object");
    XCTAssertEqualObjects([m1 get:@3], @3, @"Found object");
    XCTAssertNil([m1 get:@2], @"Removed object");
}

- (void) testIncreasing {
    int total = 100;

    FTreeSortedDictionary* map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];

    for(int i = 0; i < total; i++) {
        NSNumber* item = [NSNumber numberWithInt:i];
        map = [map insertKey:item withValue:item];
    }

    XCTAssertTrue([map count] == 100, @"Check if all 100 objects are in the map");
    XCTAssertTrue([map.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
    XCTAssertTrue([(FLLRBValueNode *)map.root checkMaxDepth], @"Checking valid depth and tree structure");

    for(int i = 0; i < total; i++) {
        NSNumber* item = [NSNumber numberWithInt:i];
        map = [map removeKey:item];
    }

    XCTAssertTrue([map count] == 0, @"Check if all 100 objects were removed");
    // We can't check the depth here because the map no longer contains values, so we check that it doesn't responsd to this check
    XCTAssertTrue([map.root isMemberOfClass:[FLLRBEmptyNode class]], @"Root is an empty node");
    XCTAssertFalse([map respondsToSelector:@selector(checkMaxDepth)], @"The empty node doesn't respond to this selector.");
}

- (void) testStructureShouldBeValidAfterInsertionA {
    FTreeSortedDictionary* map = [[[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                         insertKey:@1 withValue:@1]
                                        insertKey:@2 withValue:@2]
                                       insertKey:@3 withValue:@3];


    XCTAssertEqualObjects(map.root.key, @2, @"Check root key");
    XCTAssertEqualObjects(map.root.left.key, @1, @"Check the left key is correct");
    XCTAssertEqualObjects(map.root.right.key, @3, @"Check the right key is correct");
}

- (void) testStructureShouldBeValidAfterInsertionB {
    FTreeSortedDictionary* map = [[[[[[[[[[[[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                                  insertKey:@1 withValue:@1]
                                                 insertKey:@50 withValue:@50]
                                                insertKey:@3 withValue:@3]
                                               insertKey:@4 withValue:@4]
                                              insertKey:@7 withValue:@7]
                                             insertKey:@9 withValue:@9]
                                            insertKey:@20 withValue:@20]
                                           insertKey:@18 withValue:@18]
                                          insertKey:@2 withValue:@2]
                                         insertKey:@71 withValue:@71]
                                        insertKey:@42 withValue:@42]
                                       insertKey:@88 withValue:@88];

    XCTAssertTrue([map count] == 12, @"Check if all 12 objects are in the map");
    XCTAssertTrue([map.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
    XCTAssertTrue([(FLLRBValueNode *)map.root checkMaxDepth], @"Checking valid depth and tree structure");
}

- (void) testRotateLeftLeavesTreeInAValidState {
    FLLRBValueNode* node = [[FLLRBValueNode alloc] initWithKey:@4 withValue:@4 withColor:BLACK withLeft:
                            [[FLLRBValueNode alloc] initWithKey:@2 withValue:@2 withColor:BLACK withLeft:nil withRight:nil] withRight:[[FLLRBValueNode alloc]initWithKey:@7 withValue:@7 withColor:RED withLeft:[[FLLRBValueNode alloc ]initWithKey:@5 withValue:@5 withColor:BLACK withLeft:nil withRight:nil] withRight:[[FLLRBValueNode alloc] initWithKey:@8 withValue:@8 withColor:BLACK withLeft:nil withRight:nil]]];

    FLLRBValueNode* node2 = [node performSelector:@selector(rotateLeft)];

    XCTAssertTrue([node2 count] == 5, @"Make sure the count is correct");
    XCTAssertTrue([node2 checkMaxDepth], @"Check proper structure");
}

- (void) testRotateRightLeavesTreeInAValidState {
    FLLRBValueNode* node = [[FLLRBValueNode alloc] initWithKey:@7 withValue:@7 withColor:BLACK withLeft:[[FLLRBValueNode alloc] initWithKey:@4 withValue:@4 withColor:RED withLeft:[[FLLRBValueNode alloc] initWithKey:@2 withValue:@2 withColor:BLACK withLeft:nil withRight:nil] withRight:[[FLLRBValueNode alloc] initWithKey:@5 withValue:@5 withColor:BLACK withLeft:nil withRight:nil]] withRight:[[FLLRBValueNode alloc] initWithKey:@8 withValue:@8 withColor:BLACK withLeft:nil withRight:nil]];

    FLLRBValueNode* node2 = [node performSelector:@selector(rotateRight)];

    XCTAssertTrue([node2 count] == 5, @"Make sure the count is correct");
    XCTAssertEqualObjects(node2.key, @4, @"Check roots key");
    XCTAssertEqualObjects(node2.left.key, @2, @"Check first left child key");
    XCTAssertEqualObjects(node2.right.key, @7, @"Check first right child key");
    XCTAssertEqualObjects(node2.right.left.key, @5, @"Check second right left key");
    XCTAssertEqualObjects(node2.right.right.key, @8, @"Check second right left key");
}

- (void) testStructureShouldBeValidAfterInsertionC {
    FTreeSortedDictionary* map = [[[[[[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                            insertKey:@1 withValue:@1]
                                           insertKey:@50 withValue:@50]
                                          insertKey:@3 withValue:@3]
                                         insertKey:@4 withValue:@4]
                                        insertKey:@7 withValue:@7]
                                       insertKey:@9 withValue:@9];

    XCTAssertTrue([map count] == 6, @"Check if all 6 objects are in the map");
    XCTAssertTrue([map.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
    XCTAssertTrue([(FLLRBValueNode *)map.root checkMaxDepth], @"Checking valid depth and tree structure");

    FTreeSortedDictionary* m2 = [[[map insertKey:@20 withValue:@20]
                                       insertKey:@18 withValue:@18]
                                      insertKey:@2 withValue:@2];
    XCTAssertTrue([m2 count] == 9, @"Check if all 9 objects are in the map");
    XCTAssertTrue([m2.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
    XCTAssertTrue([(FLLRBValueNode *)m2.root checkMaxDepth], @"Checking valid depth and tree structure");

    FTreeSortedDictionary* m3 = [[[[m2 insertKey:@71 withValue:@71]
                                        insertKey:@42 withValue:@42]
                                       insertKey:@88 withValue:@88]
                                      insertKey:@20 withValue:@20]; // Add a dupe to see if the size is correct
    XCTAssertTrue([m3 count] == 12, @"Check if all 12 (minus dupe @20) objects are in the map");
    XCTAssertTrue([m3.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
    XCTAssertTrue([(FLLRBValueNode *)m3.root checkMaxDepth], @"Checking valid depth and tree structure");
}

- (void) testOverride {
    FTreeSortedDictionary* map = [[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                        insertKey:@10 withValue:@10]
                                       insertKey:@10 withValue:@8];

    XCTAssertEqualObjects([map get:@10], @8, @"Found first object");
}
- (void) testEmpty {
    FTreeSortedDictionary* map = [[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                        insertKey:@10 withValue:@10]
                                       removeKey:@10];

    XCTAssertTrue([map isEmpty], @"Properly empty");

}

- (void) testEmptyGet {
    FTreeSortedDictionary* map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];
    XCTAssertNil([map get:@"something"], @"Properly nil");
}

- (void) testEmptyCount {
    FTreeSortedDictionary* map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];
    XCTAssertTrue([map count] == 0, @"Properly zero count");
}

- (void) testEmptyRemoval {
    FTreeSortedDictionary* map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];
    XCTAssertTrue([[map removeKey:@"sometjhing"] count] == 0, @"Properly zero count");
}

- (void) testReverseTraversal {
    FTreeSortedDictionary* map = [[[[[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                           insertKey:@1 withValue:@1]
                                          insertKey:@5 withValue:@5]
                                         insertKey:@3 withValue:@3]
                                        insertKey:@2 withValue:@2]
                                       insertKey:@4 withValue:@4];

    __block int next = 5;
    [map enumerateKeysAndObjectsReverse:YES usingBlock:^(id key, id value, BOOL *stop) {
        XCTAssertEqualObjects(key, [NSNumber numberWithInt:next], @"Properly equal");
        next = next - 1;
    }];
}


- (void) testInsertionAndRemovalOfAHundredItems {
    int N = 100;
    NSMutableArray* toInsert = [[NSMutableArray alloc] initWithCapacity:N];
    NSMutableArray* toRemove = [[NSMutableArray alloc] initWithCapacity:N];

    for(int i = 0; i < N; i++) {
        [toInsert addObject:[NSNumber numberWithInt:i]];
        [toRemove addObject:[NSNumber numberWithInt:i]];
    }


    [self shuffleArray:toInsert];
    [self shuffleArray:toRemove];

    FTreeSortedDictionary* map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];

    // add them to the dictionary
    for(int i = 0; i < N; i++) {
        map = [map insertKey:[toInsert objectAtIndex:i] withValue:[toInsert objectAtIndex:i]];
        XCTAssertTrue([map.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
        XCTAssertTrue([(FLLRBValueNode *)map.root checkMaxDepth], @"Checking valid depth and tree structure");
    }
    XCTAssertTrue([map count] == N, @"Check if all N objects are in the map");

    // check the order is correct
    __block int next = 0;
    [map enumerateKeysAndObjectsUsingBlock:^(id key, id value, BOOL *stop) {
        XCTAssertEqualObjects(key, [NSNumber numberWithInt:next], @"Correct key");
        XCTAssertEqualObjects(value, [NSNumber numberWithInt:next], @"Correct value");
        next = next + 1;
    }];
    XCTAssertEqual(next, N, @"Check we traversed all of the items");

    // remove them

    for(int i = 0; i < N; i++) {
        if([map.root isMemberOfClass:[FLLRBValueNode class]]) {
            XCTAssertTrue([map.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
            XCTAssertTrue([(FLLRBValueNode *)map.root checkMaxDepth], @"Checking valid depth and tree structure");
        }
        map = [map removeKey:[toRemove objectAtIndex:i]];
    }


    XCTAssertEqual([map count], 0, @"Check we removed all of the items");
}

- (void) shuffleArray:(NSMutableArray *)array {
    NSUInteger count = [array count];
    for(NSUInteger i = 0; i < count; i++) {
        NSInteger nElements = count - i;
        NSInteger n = (arc4random() % nElements)  + i;
        [array exchangeObjectAtIndex:i withObjectAtIndex:n];
    }
}

- (void) testBalanceProblem {

    NSArray* toInsert = [[NSArray alloc] initWithObjects:@1,@7,@8,@5,@2,@6,@4,@0,@3, nil];

    FTreeSortedDictionary* map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];

    // add them to the dictionary
    for(int i = 0; i < [toInsert count]; i++) {
        map = [map insertKey:[toInsert objectAtIndex:i] withValue:[toInsert objectAtIndex:i]];
        XCTAssertTrue([map.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
        XCTAssertTrue([(FLLRBValueNode *)map.root checkMaxDepth], @"Checking valid depth and tree structure");
    }
    XCTAssertTrue([map count] == [toInsert count], @"Check if all N objects are in the map");

    // check the order is correct
    __block int next = 0;
    [map enumerateKeysAndObjectsUsingBlock:^(id key, id value, BOOL *stop) {
        XCTAssertEqualObjects(key, [NSNumber numberWithInt:next], @"Correct key");
        XCTAssertEqualObjects(value, [NSNumber numberWithInt:next], @"Correct value");
        next = next + 1;
    }];
    XCTAssertEqual(next, [[NSNumber numberWithUnsignedInteger:[toInsert count]] intValue], @"Check we traversed all of the items");

    // removing one triggers the balance problem

    map = [map removeKey:@5];

    if([map.root isMemberOfClass:[FLLRBValueNode class]]) {
        XCTAssertTrue([map.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
        XCTAssertTrue([(FLLRBValueNode *)map.root checkMaxDepth], @"Checking valid depth and tree structure");
    }
}

- (void) testPredecessorKey {
    FTreeSortedDictionary* map = [[[[[[[[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]]
                                            insertKey:@1 withValue:@1]
                                           insertKey:@50 withValue:@50]
                                          insertKey:@3 withValue:@3]
                                         insertKey:@4 withValue:@4]
                                        insertKey:@7 withValue:@7]
                                       insertKey:@9 withValue:@9];

    XCTAssertNil([map getPredecessorKey:@1], @"First object doesn't have a predecessor");
    XCTAssertEqualObjects([map getPredecessorKey:@3], @1, @"@1");
    XCTAssertEqualObjects([map getPredecessorKey:@4], @3, @"@3");
    XCTAssertEqualObjects([map getPredecessorKey:@7], @4, @"@4");
    XCTAssertEqualObjects([map getPredecessorKey:@9], @7, @"@7");
    XCTAssertEqualObjects([map getPredecessorKey:@50], @9, @"@9");
    XCTAssertThrows([map getPredecessorKey:@777], @"Expect exception about nonexistant key");
}

- (void) testEnumerator {
    int N = 100;
    NSMutableArray* toInsert = [[NSMutableArray alloc] initWithCapacity:N];
    NSMutableArray* toRemove = [[NSMutableArray alloc] initWithCapacity:N];

    for(int i = 0; i < N; i++) {
        [toInsert addObject:[NSNumber numberWithInt:i]];
        [toRemove addObject:[NSNumber numberWithInt:i]];
    }


    [self shuffleArray:toInsert];
    [self shuffleArray:toRemove];

    FTreeSortedDictionary* map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];

    // add them to the dictionary
    for(int i = 0; i < N; i++) {
        map = [map insertKey:[toInsert objectAtIndex:i] withValue:[toInsert objectAtIndex:i]];
        XCTAssertTrue([map.root isMemberOfClass:[FLLRBValueNode class]], @"Root is a value node");
        XCTAssertTrue([(FLLRBValueNode *)map.root checkMaxDepth], @"Checking valid depth and tree structure");
    }
    XCTAssertTrue([map count] == N, @"Check if all N objects are in the map");

    NSEnumerator* enumerator = [map keyEnumerator];
    id next = [enumerator nextObject];
    int correctValue = 0;
    while(next != nil) {
        XCTAssertEqualObjects(next, [NSNumber numberWithInt:correctValue], @"Correct key");
        next = [enumerator nextObject];
        correctValue = correctValue + 1;
    }
}

- (void) testReverseEnumerator {
    int N = 20;
    NSMutableArray* toInsert = [[NSMutableArray alloc] initWithCapacity:N];

    for(int i = 0; i < N; i++) {
        [toInsert addObject:[NSNumber numberWithInt:i]];
    }

    [self shuffleArray:toInsert];

    FImmutableSortedDictionary *map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];

    // add them to the dictionary
    for(int i = 0; i < N; i++) {
        map = [map insertKey:[toInsert objectAtIndex:i] withValue:[toInsert objectAtIndex:i]];
    }
    XCTAssertTrue([map count] == N, @"Check if all N objects are in the map");
    XCTAssertTrue([map isKindOfClass:[FTreeSortedDictionary class]], @"Make sure we still have a array backed dictionary");

    NSEnumerator* enumerator = [map reverseKeyEnumerator];
    id next = [enumerator nextObject];
    int correctValue = N - 1;
    while(next != nil) {
        XCTAssertEqualObjects(next, [NSNumber numberWithInt:correctValue], @"Correct key");
        next = [enumerator nextObject];
        correctValue--;
    }
}

- (void) testEnumeratorFrom {
    int N = 20;
    NSMutableArray* toInsert = [[NSMutableArray alloc] initWithCapacity:N];

    for(int i = 0; i < N; i++) {
        [toInsert addObject:[NSNumber numberWithInt:i*2]];
    }

    [self shuffleArray:toInsert];

    FImmutableSortedDictionary *map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];

    // add them to the dictionary
    for(int i = 0; i < N; i++) {
        map = [map insertKey:[toInsert objectAtIndex:i] withValue:[toInsert objectAtIndex:i]];
    }
    XCTAssertTrue([map count] == N, @"Check if all N objects are in the map");
    XCTAssertTrue([map isKindOfClass:[FTreeSortedDictionary class]], @"Make sure we still have a array backed dictionary");

    // Test from inbetween keys
    {
        NSEnumerator* enumerator = [map keyEnumeratorFrom:@11];
        id next = [enumerator nextObject];
        int correctValue = 12;
        while(next != nil) {
            XCTAssertEqualObjects(next, [NSNumber numberWithInt:correctValue], @"Correct key");
            next = [enumerator nextObject];
            correctValue = correctValue + 2;
        }
    }

    // Test from key in map
    {
        NSEnumerator* enumerator = [map keyEnumeratorFrom:@10];
        id next = [enumerator nextObject];
        int correctValue = 10;
        while(next != nil) {
            XCTAssertEqualObjects(next, [NSNumber numberWithInt:correctValue], @"Correct key");
            next = [enumerator nextObject];
            correctValue = correctValue + 2;
        }
    }
}

- (void) testReverseEnumeratorFrom {
    int N = 20;
    NSMutableArray* toInsert = [[NSMutableArray alloc] initWithCapacity:N];

    for(int i = 0; i < N; i++) {
        [toInsert addObject:[NSNumber numberWithInt:i*2]];
    }

    [self shuffleArray:toInsert];

    FImmutableSortedDictionary *map = [[FTreeSortedDictionary alloc] initWithComparator:[self defaultComparator]];

    // add them to the dictionary
    for(int i = 0; i < N; i++) {
        map = [map insertKey:[toInsert objectAtIndex:i] withValue:[toInsert objectAtIndex:i]];
    }
    XCTAssertTrue([map count] == N, @"Check if all N objects are in the map");
    XCTAssertTrue([map isKindOfClass:[FTreeSortedDictionary class]], @"Make sure we still have a array backed dictionary");

    // Test from inbetween keys
    {
        NSEnumerator* enumerator = [map reverseKeyEnumeratorFrom:@11];
        id next = [enumerator nextObject];
        int correctValue = 10;
        while(next != nil) {
            XCTAssertEqualObjects(next, [NSNumber numberWithInt:correctValue], @"Correct key");
            next = [enumerator nextObject];
            correctValue = correctValue - 2;
        }
    }

    // Test from key in map
    {
        NSEnumerator* enumerator = [map reverseKeyEnumeratorFrom:@10];
        id next = [enumerator nextObject];
        int correctValue = 10;
        while(next != nil) {
            XCTAssertEqualObjects(next, [NSNumber numberWithInt:correctValue], @"Correct key");
            next = [enumerator nextObject];
            correctValue = correctValue - 2;
        }
    }
}

@end
